Evaluation of organic matter concentration in winery wastewater: a case study from Australia

The 5-day biological oxygen demand (BOD₅) remains a key indicator for proof of compliance with environmental regulators in the monitoring and management of winery effluent. Inter-conversion factors from alternative tests that are more rapid, accurate and simpler to perform have been determined that allow prediction of BOD₅ in winery wastewaters, generally, and at different stages of production and treatment. Mean values obtained from this dataset offer rule of thumb inter-conversion factors: BOD₅ = 0.7 Chemical Oxygen Demand (COD), BOD₅ = 2.3 Total Organic Carbon (TOC) and BOD₅ = 2.7 Dissolved Organic Carbon (DOC). Specific predictive linear relationships are also provided. Out of the relationships between BOD₅vs COD, TOC and DOC, in winery wastewater, irrespective of vintage or non-vintage production periods and stage of treatment, TOC offered the most reliable prediction of BOD₅. Ethanol, glucose and fructose were evaluated in untreated wastewater as predictors of BOD₅ due to their high specificity in winery effluent. A significant relationship was determined between BOD₅ and (ethanol + glucose + fructose; R² = 0.64, n = 19; p < 0.05), but relationships between BOD₅ and ethanol and BOD₅vs (glucose + fructose) were weak (R² = 0.45 and 0.34; n = 19; p < 0.05 respectively,). There was a very strong linear correlation (y = 0.9767x + 52.8; R² = 0.97; n = 23; p < 0.05) in COD data in winery effluents when using a commercially available mercury free test kit compared with using a traditional COD test kit that contained mercury. This suggests that mercury free COD test kits could be used by the wine industry for organic pollution assessment with associated reductions to user and environmental risk, as well as reducing the costs of kit waste disposal.